Original paper

First occurrence of a Ba-dominant brewsterite: structural features

Cabella, Roberto; Lucchetti, Gabriella; Palenzona, Andrea; Quartieri, Simona; Vezzalini, Glovanna

European Journal of Mineralogy Volume 5 Number 2 (1993), p. 353 - 360

25 references

published: Apr 27, 1993
manuscript accepted: Nov 30, 1992
manuscript received: Jul 22, 1992

DOI: 10.1127/ejm/5/2/0353

BibTeX file

ArtNo. ESP147050502008, Price: 29.00 €

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Abstract The first occurrence of brewsterite in Italy, here reported, is at the Cerchiara mine (La Spezia, Liguria); it is found as prismatic crystals filling veins in metacherts from Northern Apennine ophiolitic sequences. Electron microprobe analysis ((Ba1.80Sr0.02Na0.07Ca0.03K0.04) (Al4.29Sin11.78)O32·nH2O) reveals the dominant presence of barium among the exchangeable cations. Cell parameters are: a = 6.790(1), b = 17.581(4), c = 7.735(1) Å, ß = 94.50(3)°. Biaxial (+), nα = 1.514(2), nß = 1.516(2), nγ = 1.528(2). Single crystal refinement confirms the main features of the brewsterite structure, apart from the extraframework cations which seem to be spread over three sites, two of which with low occupancy. This occurrence of brewsterite furnishes new information on the crystal chemistry of this zeolite, up to now reported only as a Sr-dominant zeolite


natural zeoliteBa-dominant brewsteriteCerchiara mine (La SpeziaItaly)chemical analysisoptical propertiescrystal structure refinement